it is known that athletic footwear must perform as a stable and comfortable support point for the body while subject to various types of stress. It is important that the shoe be comfortable and provide adequate support during the various foot movements associated with athletic activity.
Articles of footwear typically include an upper and a sole, and are sold in a variety of sizes according to the length and width of the foot. However, even feet of similar length do not necessarily have the same geometry. Therefore, the upper may be adjustable to accommodate various foot contours. Such adjustment may include medial and lateral side portions which, when tensioned, provide support to the foot. In addition, the upper may include an ankle portion which encompasses a portion of the ankle region of the foot and thereby provides support thereto.
The common way to adjust the size of a shoe is through lacing. Lacing alone, however, suffers from several disadvantages, for example, when the shoe laces or strap is drawn too tightly, the fastening system can cause pressure on the instep of the foot. Such localized pressure is uncomfortable to the wearer and can make it difficult for the shoe to be worn for prolonged periods of time. Furthermore, while such fastening systems allow the upper of the shoe to be adjustable to accommodate varying foot and ankle configurations, they do not necessarily mold to the contour of individual feet. Moreover, regardless of how much tension is exerted on the medial and lateral side portion, there still remain areas of the foot which are not supported by the upper, due to the irregular contour of the foot. Avoiding displacements between the footwear and the foot results in less strain on the ankle and other parts of the foot.
In the ski industry, there have been several attempts to provide cushioning to ski boots by using an inflatable bladder which is disposed in various locations within the ski boot. An example is found in U.S. Pat. No. 4,662,087 to Beuch. However, the technical considerations for providing cushioning to athletic shoes such as those used for basketball, tennis, aerobics and running do not parallel the technical considerations in the ski boot industry. Athletic shoes for sports such as basketball, tennis, aerobics and running have soft, flexible uppers which are stitched (not hard molded plastic as in ski boots). Additionally, athletic shoes must be relatively lightweight, inexpensive, and self-contained.
Ski boots are typically constructed to be much heavier than athletic shoes. Thus, when including a system for cushioning, such as a bladder system, the weight of the system is not a technical consideration.
Similarly, ski boots are a much more expensive consumer item than athletic shoes. Therefore, the same incremental cost of an inflatable bladder system used in ski boots cannot realistically be added to athletic shoes. Any cushioning system added to athletic shoes must be inexpensive and simple to use.
In this regard, it is imperative that athletic shoes be self-contained so that accessories, such as a detachable handheld pump, are not necessary to the operation of the cushioning system.
In short, there are numerous devices for inflating the interior of the ski boot. Generally, the devices used in the field of ski boots do not have the same requirements as in the field of athletic footwear. It is extremely important in the field of athletic footwear (e.g., basketball, running, tennis, etc.) that any inflation cushioning device be lightweight, inexpensive and must include a pump which is integral with the shoe. Ski boots are heavy. Therefore, adding the weight of an inflation or support device is of little consequence. In athletic footwear, every ounce of weight is of great importance in the performance and comfort of the shoe.
It is an object of this invention to provide footwear, which is securely fitted and fastened to the foot of the wearer, whereby a comfortable but secure grip is assured around the ankle and around the instep of the wearer.
It is a further object of this invention to provide a bladder in an athletic shoe which is lightweight, inexpensive, self-contained, and easy to use.